The goal of the Prevention and Early Treatment of Acute Lung Injury (PETAL) Network is to develop and conduct high-quality randomized, controlled clinical trials to prevent, treat and/or improve outcomes of patients with or at risk fo acute respiratory distress syndrome (ARDS) using a multidisciplinary and collaborative approach, and to collect biologic samples and clinical data necessary to determine the molecular phenotype of disease pathogenesis, response to therapy, and recovery. The specific objective of the Pacific Northwest Clinical Center is to participate in this clinical network in orer to expand upon the work we have done through the two previous ARDS Clinical Trials Networks since 1994. ARDS is a form of hypoxemic respiratory failure that is common, often fatal, and associated with significant sequelae that have a long lasting impact on the health and quality of life of its survivors. While previous trials of pharmacologic agents have failed to decrease mortality of patients with ARDS, the first two NHLBI ARDS Networks have demonstrated that changes in ventilator and fluid management can profoundly improve patient outcome. Since the publication of the landmark study of low tidal volume ventilation in 2000, there has been a steady drop in the case fatality of ARDS. The preceding NHLBI ARDS Networks proved the hypothesis that an investigator-directed network of clinical and research centers can design and conduct investigations that would improve outcomes for patients with ARDS. By expanding the focus beyond the ICU, this new network has the potential to be even more far- reaching. The proposed Pacific Northwest Clinical Center embodies the experienced, diverse, collaborative and multidisciplinary approach that will lead to PETAL's success. We are a team of academic and community hospitals; of critical care, trauma/surgical and emergency medicine specialists; and of clinical trialists, basic scientists; epidemiologists, clinicians, and research coordinators, in both Seattle, Washington and Portland, Oregon. We believe that the opportunity to improve care and both short and long-term outcomes of critically ill patients is in the hands of this new PETAL Network. In this application, we will demonstrate why the Pacific Northwest Clinical Center will be an important part of this new Network's success.